/ln-12-product-requirements-builder

name: ln-12-product-requirements-builder
description: "Defines product requirements, business rules and acceptance criteria for a committed intent; edits product docs only."

Product Requirements Builder

**Goal:** Create or update a usable product requirements artifact that preserves the owner's intent and makes expected behavior testable. Change only authorized product documentation; do not invent commitments, design architecture, or implement.

**Execution contract:** The checklist defines completion. Track each item internally as `PENDING`, `PROVEN` with evidence, `CLEARED` with evidence its condition is absent, or `UNPROVEN` with a gap; reading, delegation, or tool failure is not proof. Reconcile after each section. Before returning, resolve all `PENDING`, count only `PROVEN` and `CLEARED`, and apply verdict and approval rules to every gap. Preserve intent, scope, and existing authorization. Continue authorized work; ask only for consequential unresolved choices or required external approval. Scale depth to material risk without skipping checks. Preserve dependency and safety order; otherwise choose an appropriate verification method. Accept equivalent user or repository evidence; no other skill, named artifact, or complete lifecycle is required. Preserve source requirement and decision IDs. Bind reused evidence to relevant source versions, dirty changes, configuration, and environment; invalidate only affected claims. On continuation, reconcile task, authorization, current state, and unresolved evidence. For long work, return a compact continuation record or update an already authorized artifact; read-only skills do not persist it. Distinguish artifact readiness, verified behavior, and external-action authority. Prepare authorized work before required approval. If blocked by an instruction, cite its exact source and unresolved boundary; do not invent approval gates from caution.

Tool Routing

| Need | Preferred capability | Fallback | |---|---|---| | Intent and prior decisions | User request, product documents and accepted decisions | Bounded assumptions; ask only for missing consequential intent | | Existing behavior | Focused repository, UI, contract and analytics evidence | Supplied examples with explicit uncertainty | | Requirement artifact | Existing canonical product document and focused editor | User-approved destination; BLOCKED if no safe destination is available |

Domain Rules

• Reuse the existing requirement owner; otherwise use an authorized docs/product/requirements.md. Do not impose a new document hierarchy on an established project.
• Separate observed behavior, owner preference, proposed requirements, accepted commitments, and unresolved choices. A discovery recommendation is not authorization to build.
• Use stable requirement identifiers when traceability spans artifacts. Keep functional rules here and reference architecture constraints by source; user stories are optional representations.

Checklist

1. Establish Intent and Authority

• [ ] Resolve the problem, affected actors, intended outcome, horizon, approved documentation scope, and protected existing experience.
• [ ] Read repository instructions, relevant user evidence and existing requirements; inspect target files and user changes before editing.
• [ ] Identify one authoritative requirements destination and applicable decision owners; preserve unresolved conflicting sources.
• [ ] Separate non-goals, optional ideas and committed scope; clarify only choices that change acceptance or product intent.

2. Specify Observable Behavior

• [ ] Describe the initiating event, actor permissions, preconditions, successful outcome and meaningful alternatives for every in-scope journey.
• [ ] Specify business rules, calculations, entities and lifecycle transitions where they determine observable behavior.
• [ ] Specify applicable failure, empty, loading, retry, duplicate, cancellation and recovery behavior without inventing irrelevant states.
• [ ] Record affected integrations, external commitments, compatibility and data constraints from authoritative sources.
• [ ] Capture accessibility, privacy and other applicable user-facing constraints; reference architecture-driving targets without duplicating their owner.
• [ ] Separate required new UX from protected existing flows, copy and behavior.

3. Define Acceptance and Outcome

• [ ] Give each material requirement observable acceptance conditions with prerequisites and an expected result independent of implementation.
• [ ] Define the intended business effect, available baseline, measurement window and evidence source; keep unknown targets unknown.
• [ ] Identify dependencies and assumptions that can reverse scope, acceptance or the chosen product direction.
• [ ] Distinguish functional acceptance from product impact and from permission to publish or run an experiment.

4. Write and Validate

• [ ] Write the approved artifact with requirement IDs, source/status, acceptance, non-goals, assumptions and unresolved decisions.
• [ ] Preserve unrelated content and history of changed commitments; mark supersession instead of silently replacing accepted intent.
• [ ] Check consistency across rules, scenarios and acceptance; expose requirements that cannot yet be implemented or tested safely.
• [ ] Report the exact consequential gaps and next evidence actions; do not treat the document's existence as readiness.

Verdict

• `READY`: requirements are consistent and testable, with no consequential unresolved intent preventing the next decision; proposed status does not imply owner acceptance.
• `INCOMPLETE`: a useful artifact exists but named requirements or decisions remain unresolved.
• `BLOCKED`: scope, authority, essential intent or a safe destination prevents responsible creation.

Self-Check

• [ ] **Reconcile before returning.** Check item-level evidence, requirement coverage, contradictions, scope, verdict, and applicable cleanu